The goal of this project is to test the efficacy of a new cognitive-behavioral systems-based group treatment for persons with borderline personality disorder (BPD) and to compare it to "treatment as usual" (TAU). We elected to modify a program originally developed by Bartels and Crotty. This led us to develop STEPPS, an acronym that stands for Systems Training for Emotional Predictability and Problem Solving. Briefly, the program involves both cognitive-behavioral techniques and skills training combined with a systems component; the latter involves the patients with BPD and those in their system, including family members, friends, and health care professionals. STEPPS involves twenty 2-hour group meetings with two facilitators; the therapy is manual-based and each week specific goals are set. We propose to recruit approximately 160 adults with DSM-IV BPD during the first 2 1/2 years of the project. Subjects will be recruited through referral from area psychologists, psychiatrists, mental health clinics, and hospitals. Subjects will be screened using the Revised Diagnostic Interview for Borderlines (DIB-R) and relevant sections of the Structured Interview for DSM-IV Personality Disorders (SIDP-IV). Appropriate subjects meeting specified inclusion/exclusion criteria will be randomized to STEPPS or TAU. Subjects in both groups will be allowed to continue to see their psychiatrist, take psychotropic medication, and continue with other therapy. Baseline assessments will include the Structured Clinical Interview for DSM-IV, the SIDP- IV, the Hollingshead Scale, the Social Adjustment Scale, the Beck Depression Inventory, the Positive and Negative Affectivity Scale, the Symptom Checklist-90-R, the Barrett Impulsivity Scale, and the Medical Outcomes Study Short Form Health Survey. A new self-rated scale, the Borderline Evaluation of Severity Over Time (BEST), will also be used to rate BPD symptoms. Subjects will be assessed at baseline, and at weeks 4, 8, 12, 16, and 20. Lay and professional support system members (informants) will be asked to rate the subjects progress at specified intervals. Satisfaction with STEPPS and TAU will be assessed in informants and subjects at the conclusion of the trial. Therapy fidelity will be maintained through regular supervision, and blind ratings of videotaped sessions. Subjects randomized to STEPPS will be followed up at months 1, 3, 6, 9, and 12 post-study completion. We hypothesize that subjects participating in STEPPS will have better symptomatic improvement than subjects receiving TAU; improvement will include greater mood stability, less deliberate self-harm, less anger/impulsivity, and lower rates of health care utilization. We hypothesize that the gains of STEPPS will be maintained over 1 year. These findings should add to our understanding of the appropriate clinical management of BPD. If the efficacy of STEPPS is confirmed, future studies will include larger samples to help test whether specific subgroups will preferentially respond, and comparisons of STEPPS to other programs, including Dialectical Behavior Therapy.